The firmware is too immature in the 4570 / 4571, they are still on the first release. This drive does not write +R disks well at this time. But don't take my word for it, see the big thread here in this sub-forum.
At this time, the Benq 1655 is the drive to beat. In the future, maybe the Nec or the Liteon, but not at this point.